A series of proposed experiments are presented which are designed to determine whether or not carnosine may act as a neurotransmitter in the primary olfactory neurons of mice. Autoradiographic studies will be performed to visualize the location of carnosine in the olfactory bulb. Addtional localization information concerning carnosine and the enzymes carnosine synthetase and carnosinase will be obtained from the subcellular fractionation of olfactory bulb and olfactory epithelium. The existence of Na ion dependent high affinity uptake systems for carnosine and its precursors L-histidine and Beta-alanine will be investigated using synaptosomal preparations from olfactory bulb. Denervation experiments will be utilized to establish the cellular location of uptake systems. Subsequent to the in vivo labelling of carnosine in the olfactory bulb, a synaptosomal fraction will be prepared. This preparation will be used to study high K ion and electrically stimulated release of carnosine. Superfusion techniques will be used with anesthetized mice to demonstrate oderant, K ion, and electrically stimulated release of carnosine. Additional studies will investigate the existence and characteristics of soluble, binding and membrane, and receptor proteins for carnosine. The techniques of Dextran coated charcoal extraction, ultrafiltration, affinity chromatography, gel filtration, two-dimensional isolectric focusing - gradient electrophoresis, and fluorography will be utilized to establish the existence of, isolate, and characterize these proteins.